Musnad Ahmad 32:2070

'Affan narrated to us, Aban—meaning al-'Attar—narrated to us, Qatadah informed us, from Anas ibn Malik, from the Prophet (peace and blessings of Allah be upon him), who said: "I and the Hour have been sent like these two." And 'Affan gestured with his index finger and his middle finger.